Contrast control device for a slit-type copier exposure system

Abstract

An original document exposure device utilizes a bump exposure to control contrast by reducing the contrast in a reproduction image of the original document. The bump exposure is achieved by covering a portion of the field of view of the focusing system of an exposure lamp with a diffuse reflector. A portion of the exposure light is thus diffusely reflected into the focusing system and onto the photosensitive media. The degree of bump achieved is controlled by position adjustment of the reflector.

What is claimed is: 
     
       1. An original document exposure device, comprising: means for supporting an original;   a slit exposure system for illuminating a slit area on the original, said exposure system including a light source for directing exposure light onto a supported original and means for directing reflected exposure light from within a field of view of the original toward a photosensitive media;   means for producing relative motion between said original supporting means and said exposure system to scan said exposure light and said field of view over the original;   diffuse reflector means for receiving a portion of the exposure light from said light source and diffusely reflecting said exposure light; and   adjustable reflector positioning means for positioning said reflector means between said supporting means and said exposure system to block a portion of said field of view, and to adjust the relative portion of said field of view blocked by said reflector means.   
     
     
       2. A device as defined in claim 1, wherein said adjustable reflector positioning means includes means for selectively moving said reflector means into and out of said field of view. 
     
     
       3. A device as defined in claim 2, wherein said original supporting means includes a planar support for the original, said diffuse reflector means defines a planar reflective surface, said reflective surface being disposed in a first plane parallel to said planar support, and wherein said selective moving means moves said reflective surface within said first plane. 
     
     
       4. A device as defined in claimed 3, wherein said selective moving means moves said reflective surface perpendicular to said slit. 
     
     
       5. A device as defined in claim 3, wherein said diffuse reflector means is a planar reflector plate. 
     
     
       6. A device as defined in claim 5, further comprising means for selectively moving said plate in a direction perpendicular to said slit.